Synthesis, characterization and use of enzyme cashew gum nanoparticles for biosensing applications.

This research reports, for the first time, the immobilization of an enzyme - Rhus vernificera laccase - on cashew gum (CG) nanoparticles (NPs) and its application as a biological layer in the design and development of an electrochemical biosensor. Laccase-CG nanoparticles (LacCG-NPs) were prepared by the nanoprecipitation method and characterized by UV-Vis spectrophotometry, atomic force microscopy, scanning electron microscopy, attenuated total reflectance-Fourier-transform infrared spectroscopy, circular dichroism, cyclic voltammetry, and electrochemical impedance spectroscopy. The average size and stability of the NPs were predicted by DLS and zeta potential. The ATR-FTIR results clearly demonstrated an interaction between -NH and -OH groups to form LacCG-NPs. The average size found for LacCG-NPs was 280 ± 53 nm and a polydispersity index of 0.309 ± 0.08 indicated a good particle size distribution. The zeta potential shows a good colloidal stability. The use of a natural product to prepare the enzymatic nanoparticles, its easy synthesis and the immobilization efficiency should be highlighted. LacCG-NPs were successfully applied as a biolayer in the development of an amperometric biosensor for catechol detection. The resulting device showed a low response time (6 s), good sensitivity (7.86 µA µM-1 cm-2), wide linear range of 2.5 × 10-7-2.0 × 10-4 M, and low detection limit (50 nM).

Extraction, Purification, and Characterization of Polysaccharides of Araucaria heterophylla L and Prosopis chilensis L and Utilization of Polysaccharides in Nanocarrier Synthesis.

BACKGROUND: Plant gums consist of polysaccharides which can be used in the preparation of nanocarriers and provide a wide application in pharmaceutical applications including as drug delivery agents and the matrices for drug release. The objectives of the study were to collect plant gums from Araucaria heterophylla L and Prosopis chilensis L and to extract and characterize their polysaccharides. Then to utilize these plant gum-derived polysaccharides for the formulation of nanocarriers to use for drug loading and to examine their purpose in drug delivery in vitro. METHODS: Plant gum was collected, polysaccharide was extracted, purified, characterized using UV-Vis, FTIR, TGA and GCMS and subjected to various bioactive studies. The purified polysaccharide was used for making curcumin-loaded nanocarriers using STMP (sodium trimetaphosphate). Bioactivities were performed on the crude, purified and drug-loaded nanocarriers. These polysaccharide-based nanocarriers were characterized using UV-Vis spectrophotometer, FTIR, SEM, and AFM. Drug release kinetics were performed for the drug-loaded nanocarriers. RESULTS: The presence of glucose, xylose and sucrose was studied from the UV-Vis and GCMS analysis. Purified polysaccharides of both the plants showed antioxidant activity and also antibacterial activity against Bacillus sp. Purified polysaccharides were used for nanocarrier synthesis, where the size and shape of the nanocarriers were studied using SEM analysis and AFM analysis. The size of the drug-loaded nanocarriers was found to be around 200 nm. The curcumin-loaded nanocarriers were releasing curcumin slow and steady. CONCLUSION: The extracted pure polysaccharide of A. heterophylla and P. chilensis acted as good antioxidants and showed antibacterial activity against Bacillus sp. These polysaccharides were fabricated into curcumin-loaded nanocarriers whose size was below 200 nm. Both the drug-loaded nanocarriers synthesized using A. heterophylla and P. chilensis showed antibacterial activity with a steady drug release profile. Hence, these natural exudates can serve as biodegradable nanocarriers in drug delivery.

Effect of extraction temperature on rheological behavior and antioxidant capacity of flaxseed gum.

Soluble flaxseed gum (SFG) extracted at different temperatures (25, 40, and 60 °C) was analyzed in relation to the yield, polysaccharides and phenolics composition, surface charge, color, and rheological properties. The yield of SFG extract increased as the extraction temperature increased. The SFG xylan was the main component regardless the extraction temperature, but a reduction of substituents on the xylose chain was observed when increasing the extraction temperature. The phenolic compounds were also affected by the extraction temperature, influencing the antioxidant capacity of the gum. For all the extraction temperatures, SFG aqueous solutions showed a shear time-independent and shear-thinning behavior. Furthermore, oscillatory measurements showed a prevailing viscous character, but the decrease of the extraction temperature resulted in an increase of both G' and G". Therefore, SFG extracted at low extraction temperatures showed higher viscous and elastic properties, while high extraction temperatures increased the antioxidant activity.

Application of high-pressure homogenization on gums.

High-pressure homogenization (HPH) is an emerging process during which a fluid product is pumped by pressure intensifiers, forcing it to flow through a narrow gap, usually measured in the order of micrometers. Gums are polysaccharides from vegetal, animal or microbial origin and are widely employed in food and chemical industries as thickeners, stabilizers, gelling agents and emulsifiers. The choice of a specific gum depends on its application and purpose because each form of gum has particular values with respect to viscosity, intrinsic viscosity, stability, and emulsifying and gelling properties, with these parameters being determined by its structure. HPH is able to alter those properties positively by inducing changes in the original polymer, allowing for new applications and improvements with respect to the technical properties of gums. This review highlights the most important advances when this process is applied to change polysaccharides from distinct sources and molecular structures, as well as the future challenges that remain. © 2017 Society of Chemical Industry.

Antidiarrheal activity of cashew GUM, a complex heteropolysaccharide extracted from exudate of Anacardium occidentale L. in rodents.

ETHNOPHARMACOLOGICAL RELEVANCE: Anacardium occidentale L. (Anacardiaceae) is commonly known as the cashew tree. It is native to tropical America and extracts of the leaves, bark, roots, chestnut net and exudate have been traditionally used in northeast Brazil for the treatment of various diseases. The exudate of the cashew tree (cashew gum) has been exploited by locals since ancient times for multiple applications, including the treatment of diarrheal diseases. AIM OF THE STUDY: The primary aim of the present study is to evaluate the antidiarrheal activity of cashew gum (CG), a complex heteropolysaccharide from the exudate of the cashew tree, using various models. MATERIALS AND METHODS: The antidiarrheal activity of cashew gum (CG) against acute diarrhea was investigated using the castor oil-induced diarrhea model. The effects of CG on gastrointestinal transit and castor oil- and PGE2- induced enteropooling were also examined in rodents. In addition, the effect of CG against secretory diarrhea was investigated using a model of fluid secretion in cholera toxin-treated intestinal closed loops in live mice. RESULTS: Cashew gum (30, 60, and 90 mg/kg, p.o.) showed a significant (P<0.05-0.01) antidiarrheal effect in rats with castor oil-induced diarrhea, inhibiting the total amount of stool and diarrheal stools. The 60 mg/kg dose of CG exhibited excellent antidiarrheal activity and significantly reduced the severity of diarrhea (diarrhea scores) in rats. CG (60 mg/kg) significantly (P<0.05) decreased the volume of castor oil- and PGE2-induced intestinal fluid secretion (enteropooling). In addition, similar to loperamide (standard drug, 5 mg/kg, p.o.), CG treatment reduced the distance traveled by a charcoal meal in the 30-min gastrointestinal transit model by interacting with opioid receptors. In cholera toxin-induced secretory diarrhea, CG (60 mg/kg) significantly inhibited the intestinal fluid secretion and decreased Cl(-) ion loss in the cholera toxin(-)treated isolated loops model of live mice by competitively binding to cholera toxin-GM1 receptors. CONCLUSIONS: In conclusion, our results indicate that a complex heteropolysaccharide extracted from the exudate of A. occidentale L. has antidiarrheal activity in acute, inflammatory, and secretory diarrhea models, which could justify its traditional use in the treatment of diarrhea in northeast Brazil. The antidiarrheal activity might be explained by the capacity of CG to inhibit gastrointestinal motility and thereby reduce the accumulation of intestinal fluid and the secretion of water and chloride ions in the lumen of the intestine.

Gastroprotective properties of cashew gum, a complex heteropolysaccharide of Anacardium occidentale, in naproxen-induced gastrointestinal damage in rats.

Long-term use nonsteroidal anti-inflammatory drug is associated with gastrointestinal (GI) lesion formation. The aim of this study was to investigate the protective activity of cashew gum (CG), a complex heteropolysaccharide extracted from Anacardium occidentale on naproxen (NAP)-induced GI damage. Male Wistar rats were pretreated with vehicle or CG (1, 3, 10, and 30 mg/kg, p.o.) twice daily for 2 days; after 1 h, NAP (80 mg/kg, p.o.) was administered. The rats were euthanized on the 2nd day of treatment, 4 h after NAP administration. Stomach lesions were measured using digital calipers. The medial small intestine was used for the evaluation of macroscopic lesion scores. Samples of the stomach and the intestine were used for histological evaluation, and assays for glutathione (GSH), malonyldialdehyde (MDA), and myeloperoxidase (MPO). Additional rats were used to measure gastric mucus and secretion. Pretreatment with CG reduced the macroscopic and microscopic damage induced by NAP. CG significantly attenuated NAP-induced alterations in MPO, GSH, and MDA levels. Furthermore, CG returned adherent mucus levels to normal values. These results suggest that CG has a protective effect against GI damage via mechanisms that involve the inhibition of inflammation and increasing the amount of adherent mucus in mucosa.

Structural characterization of a glucuronoarabinoxylan from pineapple (Ananas comosus (L.) Merrill) gum exudate.

Native polysaccharide from pineapple gum (PANP) was obtained following alkaline extraction of gum and fractionation with cetylpyridinium chloride. It was characterized as a glucuronoarabinoxylan using NMR, methylation data, controlled Smith degradation, carboxy-reduction, and ESI-MS of oligosaccharides produced on mild acid hydrolysis of PANP. HSPEC-MALLS-RI of carboxy-reduced fraction showed homogeneous profile (Mw 1.943×10(5) g/mol). PANP was composed of Ara, Xyl, Gal, and GlcpA (40:23:7:30 molar ratio). Its main chain presented (1→4)-linked ß-xylan, highly substituted at O-2 and O-3 by side chains of 3-O- and 3,5-di-O-linked α-Araf, 2-O- and 4-O-linked α-GlcpA, and nonreducing end-units of α-Araf, ß-Arap, ß-Galp, and α-GlcpA. ESI-MS of a mixture of oligosaccharides formed on the mild acid hydrolysis of PANP was consistent with repetitive structures of α-GlcpA O-3 linked at ß-Xylp units, whereas in others glucuronoarabinoxylan-type gum exudates, α-GlcpA units had been previously found to be linked at O-2.

Electrospinning of commercial guar-gum: Effects of purification and filtration.

Guar gums of two different commercial sources were successfully electrospun on both mica and copper tape at several concentrations starting from 1% (w/w). The electrospun fibers formed with the raw materials were not uniform and presented aggregates and beads within the fibers. Two different purification procedures and a filtration sequence with different pore size membranes were applied to enhance galactomannan solution homogeneity and solubility. The consequence was improved fiber morphology. We observed that the precipitation step, within the purification procedure, produced changes in the molar mass distribution and yielded different fiber diameter. Furthermore, spherical aggregates between fibers and within them disappeared after the sequential filtration. The resulting electrospun fiber diameter decreased with membrane pore diameter reduction. We conclude that the filtration process is responsible for molecular disentanglement, as well as disaggregation, which leads to improved electrospun galactomannan fiber morphology.

Purification of guar gum for biological applications.

Commercial guar gum (GG) was purified by four different methods and characterized by gel permeation chromatography (GPC), thermogravimetric analysis and the determination of monosaccharides composition, protein and copper content, turbidity, intrinsic viscosity and rheological parameters. The first method was based on enzymatic hydrolysis with porcine pancreatin. In the second method successive gum dissolution, centrifugation and precipitation with acetone and ethanol were carried out. Precipitation with Fehling solution was employed in the third method. In the fourth method, the gum was purified by method 2 and then by method 3. All methods led to a reduction in protein content, arabinose and glucose residues, considered as sugar contaminants, and also in intrinsic viscosity and molar mass. Total elimination of protein was only achieved by method 4. Using methods 3 and 4, the gum was contaminated with small amounts of Cu(II) from the Fehling solution. Methods 2 and 4 apparently provided purer guar gum. If the amount of protein is a crucial parameter in the biological application and the guar will be taken in low amounts, method 4 is recommended. Taking into account the purity, thermal stability, rheological parameters of the purified gum and also the cost and simplicity of the procedure, method 2 has wider biological application.